1. Field of the Invention
The invention relates to a one-way clutch.
2. Description of the Related Art
A one-way clutch is used for various types of equipment (see, for example, Japanese Patent Application Publication No. 2013-257024 (JP2013-257024 A)), by way of example, for an alternator in an automobile. As depicted in FIG. 6, a one-way clutch includes an inner ring 90, an outer ring 91, a plurality of rollers 92, an annular cage 93, and springs 94. The rollers 92 are provided between the inner ring 90 and the outer ring 91. The cage 93 holds the rollers 92. The springs 94 bias the rollers 92. A plurality of cam surfaces 95 is formed on an outer periphery of the inner ring 90. A wedge-like space 100 is formed between each of the cam surfaces 95 and an inner peripheral surface 91a of the outer ring 91. One roller 92 is provided in each of the wedge-like spaces 100. A one-way clutch for an alternator is configured such that the outer ring 91 rotates integrally with a pulley.
In the one-way clutch, when the rotational speed of the outer ring 91 is higher than the rotational speed of the inner ring 90 and the outer ring 91 rotates relative to the inner ring 90, each of the rollers 92 is engaged between the corresponding cam surface 95 and the outer ring 91. This makes the inner ring 90 and the outer ring 91 unable to rotate relative to each other. When the rotational speed of the outer ring 91 is lower than the rotational speed of the inner ring 90, the rollers 92 are disengaged from the inner ring 90 and the outer ring 91. This makes the inner ring 90 and the outer ring 91 rotatable relative to each other.
When the one-way clutch as depicted in FIG. 6 is assembled, the annular cage 93 needs to be provided on the outer periphery of the inner ring 90. To achieve this, the cage 93 may be moved in an axial direction toward the inner ring 90 and assembled on the inner ring 90. To allow the one-way clutch to function as described above, the rollers 92 held by the cage 93 need to be allowed to engage appropriately with the cam surfaces 95 of the inner ring 90. Consequently, management of the positions of the inner ring 90 (cam surfaces 95) and the rollers 92 in an axial direction is important.
The cage 93 has a pair of annular portions 97, 97 and a plurality of cage bars 96 connecting the annular portions 97, 97 together. The rollers 92 are held by the annular portions 97, 97 so as to restrict movement of the rollers 92 in the axial direction. Thus, position management for the inner ring 90 (cam surfaces 95) and the rollers 92 in the axial direction substantially corresponds to position management for the inner ring 90 and the cage 93 in the axial direction.
In the conventional one-way clutch, as depicted in FIG. 7, recessed grooves 98 allowing formation of the respective cam surfaces 95 are formed on an outer peripheral surface of the inner ring 90 so as to be elongate in the axial direction. An axial end of each of the recessed grooves 98 is formed as an inclined surface 98a. Protruding portions 99 are provided on an inner periphery of each of the annular portions 97 of the cage 93. During assembly, when the cage 93 is moved in the axial direction with respect to the inner ring 90 (when, in FIG. 7, the cage 93 is moved in the direction of arrow X), each protruding portion 99 comes into contact with the corresponding inclined surface 98a and rides on the inclined surface 98a. Eventually, movement of the protruding portions 99 is restricted.
In the related art, each protruding portion 99 of the cage 93 rides on the corresponding inclined surface 98a of the inner ring 90 to position the cage 93 with respect to the inner ring 90 in the axial direction. However, in this case, the position of the cage 93 in the axial direction fails to be constant due to the magnitude of a load imposed on the cage 93 to move the cage 93 and an error in production accuracy (inclination angle) of the inclined surfaces 98a. The positioning of the cage 93 (the rollers 92 held by the cage 93) with respect to the inner ring 90 is unstable, leading to a possible increase in assembly error.